Upper Mississippi River System Changes in Floodplain Inundation from 1940 to 2022

Floodplain inundation is believed to be the dominant physical driver of an array of ecosystem patterns and processes in the Upper Mississippi River System (UMRS). Here, we present results of a change analysis to estimate shifts in floodplain inundation regime characteristics from 1940 to 2022 in navigation pools 3 through 10 along the Upper Mississippi River. Data were derived from a geospatial model of surface water inundation developed for the UMRS and described in Van Appledorn et al. (2021; doi: 10.1002/rra.3628) and published datasets of daily inundation depth for the growing seasons (1 April – 30 September) from 1940 to 2022 (Van Appledorn et al. 2024). We excluded areas permanently wetted (aquatic areas), surfaces in agricultural production, roads, and developed areas. Using the depth times series data, we identified inundation events as sequential days where depths were greater than zero from 1940 to 2022 at each pixel in the modeling domain. We then characterized patterns of inundation event frequency, duration, depth, and timing on annual time steps and fitted linear regression models of these patterns to assess changes over the period of record. Based on model results, we calculated change estimates to compare estimates of flood regime conditions in 2022 to those of 1940. The data are intended for use in geospatial analyses of floodplain ecosystem patterns and processes.